1661731200 has 288 divisors, whose sum is σ = 6151923960. Its totient is φ = 442920960.

The previous prime is 1661731177. The next prime is 1661731229. The reversal of 1661731200 is 21371661.

1661731200 is a `hidden beast` number, since 16 + 617 + 31 + 2 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×1661731200² = 5522701162106880000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 776532 + ... + 778668.

Almost surely, 2^1661731200 is an apocalyptic number.

1661731200 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661731200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3075961980).

1661731200 is an abundant number, since it is smaller than the sum of its proper divisors (4490192760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661731200 is an equidigital number, since it uses as much as digits as its factorization.

1661731200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2176 (or 2147 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 1661731200 is about 40764.3373550951. The cubic root of 1661731200 is about 1184.4596158128.

The spelling of 1661731200 in words is "one billion, six hundred sixty-one million, seven hundred thirty-one thousand, two hundred".